1. AJ/FormS

    AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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    I can tell you that ;
    34 +74 +180 =288* intake duration and
    70 +34 +180 =284* exhaust duration,
    For a clutch car, that could be ground on a 108 LSA and that would make the overlap to be 70*, making it a hi-rev narrow powerband cam..
    11.4mm is .449 inch, and 11.6 is .457

    Depending on the tappet rise that the specs were taken at,
    that could be a very big cam. It would take a lot of compression ratio to make it work properly, especially in a small engine.... Back then, we had the pump-gas for that, to prevent detonation..... but today we do not.
    Without adequate cylinder pressure, I fear it would make a lousy street-cam, especially in a clutch car, as the bottom end would go soft in a hurry.
    From the numbers, in a 318, this would want 11/1 Scr at 600ft elevation, to make ~160psi. And from idle to ~3000 rpm it will still feel like a ~273. At 8/1 the pressure is predicted to be just 106psi, and she would be feeling like ~180 cubes down low.
    But I suspect this is a mechanical lifter cam, and so, the lash will eat some of this duration up. And probably the lift a well. So the bottom end might not feel as sad as the numbers might indicate.

    Back in the 60s, there were less than a handful of cam grinders around.

    good luck with your search.
     
  2. Lamm

    Lamm New Member

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    Thanks for the reply.

    I have similar thoughts about that camshaft. Like you said, this is a mechanical lifter cam, so I agree because it had an early 273 engine. The classification book gives that engine 10.5 scr.

    I haven’t really found quite the same camshaft yet. The same style cam is for me the Isky Model: 390177. Am I right?
     
  3. volaredon

    volaredon Well-Known Member

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    I dunno. Every cam I have ever looked at for a Chrysler slant 6 or V8 has had dimensions in fractional inches not mm.
     
  4. Dartswinger70

    Dartswinger70 Catch a wave youll be sittin on top of the world

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    Im thinking 318 has these single coil valve springs anything even close to mild for a 340 is going to need springs, although i ran a summit .444/.444 lift cam in a 318 with stock valve springs, it seemed to pull of to a point maybe 5500 rpm as i recall...
     
  5. Dartswinger70

    Dartswinger70 Catch a wave youll be sittin on top of the world

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    You must be lookin at "Chinese " cams...LOL!
     
  6. volaredon

    volaredon Well-Known Member

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    Nope. I steer clear of Chineseium as much as possible!!!
     
  7. AJ/FormS

    AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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    I dunno what type of engine you might be building that this type of specification interests you. I only have experience with street combos, and ZERO experience with the 273. So, I urge you to give an ear to the guys that do have 273 experience.
    on that note;

    IF:
    1) that 288 cam was at Zero-lift, and I doubt it was, and
    2) that cam was on a 108LSA
    Then, that cam is messed up for street, and;
    installed at split-overlap it would look something like this ;
    288/107/111/284/70... which is;
    Intake/compression/power/exhaust/Effective overlap, and
    with an Ica of 73*
    In a 273, on the street, with a clutch
    it would need 11/1 Scr, just to get moving, because, in the low rpm range,it would make power like a slightly warmed up 225slanty. It would need to go into a lightweight car with a lotta gear. The cam wants to make it's power at say 5800 rpm,to be shifted at around 6200,
    But I doubt you could get the 1960s era heads to go there.
    But if you could, with the typical 3.55 gears, and 25.5" tires, at WOT, that would be 50 mph in 2.66 Low gear/69 in Second.
    But at 32 mph, the rpm will be in turtle-slow territory, namely;
    2870 in Second/3980 in First. With a 5800rpm powerpeak, you might expect a torque peak around 4300, so at 3980 that little 273 engine with that big 288 cam is struggling to get back up on the power. I guarantee you, that will be frustrating; more so in Second or Third gear.

    But like I said; I doubt the actual lift after lashing will be anywhere near 288/284
    Sometimes, mechanical cams are advertised at .020 tappet rise. and the lash might be .020 on a cam like that. But the lash is measured at the valve, whereas the lift is at the tappet. So you cannot even get a sliver of an idea as to what the actual duration of that cam might be.
    What I mean is this;
    .020 tappet rise, on the other side of the 1.5 ratio rocker-arm is .020 x 1.5= .030 rocker-arm motion.
    IF the lash was .030. then NOW you are at zero-lash and zero valve motion.
    but if the lash was .020, then the valve is already .030 less .020=.010 off the seat. But how much duration was used up in this exercise, is anybody's guess.
    What if it was just 6 degrees. And what if the closing action was also 6 degrees. That is a total of 12 degrees used up in the lashing procedure, and so;
    288 less 12 =276*NET duration after lashing.
    Ok so;
    I'm making this stuff up as I go, so I have zero ideas about this cam. But you can see how a person might get caught up in the specs, and build a disappointing STREET combo. This is VERY easy to do with a small engine like a 273, and especially so with a long-period cam..

    Additionally; if you are looking to build a performance street car with a 273, then, I highly recommend a solid-lifter mechanical cam ........................... just probably not this one .................. unless perchance you can get more pertinent, and useful information about it.
    Furthermore
    with such a small engine, the elevation at which it will be operating in, becomes very important, because, as the engine travels ever higher, the cylinder pressure drops ever lower. If you are starting with a modest cylinder pressure, it doesn't take much change in elevation before the powerloss becomes very noticeable. The change is about 1/2psi per 100 ft.
    For example;
    a true 10:1 273, at sealevel with 165psi cranking cylinder pressure, at 2500, the pressure is predicted to have dropped to 153. And by 5000 the pressure is perhaps just 140. This is with no changes made.
    With modest starting pressure of 145, by 5000 the pressure could be as low as 120, which IMO, is for lawnmowers, lol.
    As the engine goes up, the air is less dense, and so the carb will go ever richer, and that is a double whammy for her, loosing even more power.
    I'm just trying to be helpful, as I noticed your location.
     
    Last edited: Aug 4, 2021
  8. Lamm

    Lamm New Member

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    Those dimensions are more likely to be reported in metric because the competitions were in Europe. I would believe that cars and their engines were still developed in the United States

    I was thinking of a hairy street engine, but with some vintage race parts. Something like this: high CR, ported iron heads, headers and a single plane intake manifold.

    That’s why I thought Chrysler’s own racing camshaft could be fun ..
     
  9. AJ/FormS

    AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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    Aha!
     
  10. AJ/FormS

    AJ/FormS 68 B'cuda fb, Form S clone ... 367/A833/3.55s

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    Well; as to the degree of hairiness,
    to me, it sorta looks like you kindof painted yourself into a corner, with the 9.61Scr,iron heads, and a hydraulic roller cam.
    But, the solid roller is a step in the right direction.

    at this power level the single-plain is an option.I would NOT run it with that XR274 at your CCP. I run the dual-plain AirGap, and it's pretty amazing. With it, my 367 will pull itself, down at 550/500 rpm in 10.97 First gear (manual trans), with an Ica of 66*. And it has made hundreds of pulls to 7000/7200. Maybe thousands .....
    Long-tubes are a must-have.
    IMO, a modern cam is a better idea. They usually; have faster ramps, more lift at the same durations, the profiles are smoother, and they are usually quieter, and last longer.

    If you want hairy, push the pressure to the moon, and run an anti-detonant when required.
    That was my thought when I built my combo. Why should I sacrifice all my bottom-end and a good part of my midrange with low-pressure thought I, where some 90/95% of my driving is; just to make sure the engine lives at WOT. I was fully prepared to install a water/meth injection system, in the event I miscalculated. When it ran on 87E10 (alloy heads) you can only imagine how ecstatic I was.
     
    Last edited: Aug 5, 2021
  11. Dan the man

    Dan the man Well-Known Member

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    Hello everybody, I've been away from the car scene for awhile. I know that this is for cams, but while reading it I thought of a question that I know is off topic here, but what's a good budget cylinder head for a 318? I'm thinking about putting together a 318 for fun. Not concerned with lots of power, maybe 300 horsepower or so at the flywheel. Also I've been looking for a clean rust free duster or dart with power steering and ac. No project cars and car needs to be close to st.louis mo. Thanks
     
  12. RustyRatRod

    RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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    Not to sound like a smartass....because I'm not bein one, but you'd get better responses if you created a thread all your own in the small block section. I'll look for it.
     
  13. Dan the man

    Dan the man Well-Known Member

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    Thanks. I understand
     
  14. Brooks James

    Brooks James Dustoff

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    I have a 512 lift cam in my magnum
    There Is only 20 thousandth clearance between the retainer and valve guide
    Completely stock except for the cam and valve springs
     
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    • RammerJammer75

      RammerJammer75 Well-Known Member

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      Is that actual lift measured at the valve or what the cam card says? Not being smart, but if it's stated .512" lift on the cam, it's actually less than .500" due to pushrod deflection, valvetrain geometry etc.
       
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      • Bewy

        Bewy Well-Known Member

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        Measured lift can be more than what the cam card states, due to the variables in the valve train.
        David Vizard tested 23 BB Chev rockers. The overall ratio was greater than the advertised ratio for the majority.
         
      • RustyRatRod

        RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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        .020" is not enough.
         
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        • MOPAROFFICIAL

          MOPAROFFICIAL FABO Gold Member FABO Gold Member

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          Probably .490 something unless the geometry is off to the inside.
           
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